Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
  • A61M5/142—Pressure infusion, e.g. using pumps
• • G—PHYSICS
  • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
  • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
  • G16H20/00—ICT specially adapted for therapies or health-improving plans, e.g. for handling prescriptions, for steering therapy or for monitoring patient compliance
  • G16H20/10—ICT specially adapted for therapies or health-improving plans, e.g. for handling prescriptions, for steering therapy or for monitoring patient compliance relating to drugs or medications, e.g. for ensuring correct administration to patients
  • G16H20/17—ICT specially adapted for therapies or health-improving plans, e.g. for handling prescriptions, for steering therapy or for monitoring patient compliance relating to drugs or medications, e.g. for ensuring correct administration to patients delivered via infusion or injection
• • G—PHYSICS
  • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
  • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
  • G16H40/00—ICT specially adapted for the management or administration of healthcare resources or facilities; ICT specially adapted for the management or operation of medical equipment or devices
  • G16H40/60—ICT specially adapted for the management or administration of healthcare resources or facilities; ICT specially adapted for the management or operation of medical equipment or devices for the operation of medical equipment or devices
  • G16H40/63—ICT specially adapted for the management or administration of healthcare resources or facilities; ICT specially adapted for the management or operation of medical equipment or devices for the operation of medical equipment or devices for local operation
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
  • A61M5/142—Pressure infusion, e.g. using pumps
  • A61M2005/14208—Pressure infusion, e.g. using pumps with a programmable infusion control system, characterised by the infusion program
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2202/00—Special media to be introduced, removed or treated
  • A61M2202/04—Liquids
  • A61M2202/0468—Liquids non-physiological
  • A61M2202/048—Anaesthetics
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2205/00—General characteristics of the apparatus
  • A61M2205/18—General characteristics of the apparatus with alarm
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2205/00—General characteristics of the apparatus
  • A61M2205/33—Controlling, regulating or measuring
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
  • A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
  • A61M5/172—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body electrical or electronic
  • A61M5/1723—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body electrical or electronic using feedback of body parameters, e.g. blood-sugar, pressure
• • G—PHYSICS
  • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
  • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
  • G16H50/00—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics
  • G16H50/50—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics for simulation or modelling of medical disorders

Definitions

• the present invention relates to apparatuses and methods for controlling and steering intravenous anesthesia
• IVA intravenous drugs
• IVA intravenous drugs
• other intravenous drugs to a patient in a safe and user friendly way.
• Via the systems of the invention less experienced anesthetists profit from expert knowledge stored, retrievable and usable via the system.
• IVA Intravenous anesthesia
• Anesthetic drugs include hypnotics to control hypnosis of the patient, morphinomimetics to control analgesia and curare for muscle relaxation.
• these drugs were applied manually by the anesthetist via syringes.
• the traditional titration process is time-consuming, labor- intensive and vulnerable to human errors.
• there is a factor of unpredictability involved which is caused among others by patient variability and which can not fully be taken into account by pharmacodynamic and/or pharmacokinetic models.
• the anesthetist is multi-tasked both physically and cognitively during the course of a surgical operation. It is known that human errors are ready to incur upon repetitive tasks such as the constant monitoring of electronic and other signals, the repetitive delivery of drugs via injections etc.
• the human brain is very performing regarding the taking of decisions in complex situations; but when a human being has to survey continuously a monotonous parameter the performance of the human brain falls with an increased hazard for accidents (Schreiber, 1990, Reanim 15: 287-97) .
• the patient not only benefits from the reduction of risks, there are other advantages linked to better controlled IVA. It has for instance been demonstrated that a fast recovery from a surgical lung transplantation without complications and a fast decoupling from mechanical ventilation apparatuses benefits the patient (Westerlind, JCTVA, 1999, Tran
• IVA intravenous anesthesia
• Target-controlled infusion (TCI) apparatuses introduced onto the market comprise an infusion pump attached to a computer (microprocessor).
• the computer's program contains a pharmacokinetic model, describing the elimination and metabolism of the drug within the body, and pharmacokinetic data for widely different patient populations.
• the target drug concentration and data specific to the patient undergoing surgery, such as age and body weight, are entered into the system by the anesthetist. From its pharmacokinetic model, the TCI system determines the initial loading dose required to achieve the target concentration and the infusion rate to sustain it, and controls the infusion automatically (http : //www .
• Patent application O99/10029 relates to an automated medication infusion device. It receives prescription information including information pertaining to a medication prescribed for a patient .
• the system is only capable of performing predefined tasks . It does not contain any intelligence to propose any other action than merely alerting a clinician when the prescribed medication is found inappropriate to administer to the patient.
• Aims of the invention It is an aim of the present invention to provide computer-assisted systems and methods that allow transfer of the knowledge of an expert, preferably an anesthetist expert, to other anesthetists and/or to other (trained) medical personnel such as nurses or medical assistants.
• the improved IVA systems and methods of the invention are flexible, easy to use and transparent.
• the improved intravenous anesthesia protocols and steering systems of the invention allow optimal anesthesia and recovery therefrom.
• the systems and methods of the invention are equally well applicable in cancer therapy wherein intravenous drugs are used. Description of the figures
• the figure 1 represents a flow chart showing interactions between different components of the system.
• the figure 2 represents the available interfaces of the Session Controller and their usage .
• the figure 3 represents the available interfaces of the Infusion Controller and their usage.
• the figure 4 represents the available interfaces of the Datalogger Controller and their usage.
• the figure 5 represents the available interfaces of the Communication Controller and their usage.
• a first aspect of the invention relates to a system for computer-aided intravenous delivery of anesthetics and/or other drugs to a patient .
• the system comprises : an Infusion Controller that delivers an amount of drug(s) to a patient; possibly a DataLogger Controller with one or more Sensors adapted so as to be coupled to a patient and to generate signals reflecting one or more health conditions or statuses of the patient; a Communication Controller connected with the infusion pumps and/or monitors; a Session Controller that carry out the modeling of the anesthesia procedures established or proposed by an expert (in term of procedures, tools, constraints, interaction and event tables) .
• the session controller is arranged to run a first procedure and to dynamically adapt said first procedure and/or to select and run a second procedure based upon one or more of said sensors' output and/or observation from a physician ; a Graphic User Interface to display different views of the system and to accept user input; a set of interfaces used to link the Infusion, Datalogger (if present) and Session Controllers to views displayed by the Graphical User Interface; a Processor or Infusion Session Manager that integrates the User Interface, the Infusion Controller, the Datalogger Controller (if present) , the Communication Controller and the Session Controller and that steers drug delivery.
• the system according to the invention differs from the prior art in that it introduces a modeling of (anesthetic) procedures in a way that reliable expert knowledge is passed onto the anesthetist in charge of the operation and/or his assistant of that day .
• the system of the invention hereto contains a set of configurable written procedures to steer intravenous anesthetic drug delivery and/or other drug delivery, whereby said procedures have been adapted to the type of surgical action and/or therapy, adapted to the patient's physical condition, and adapted to the type of drugs, tools and theoretical models used.
• the set of procedures (which reflect the knowledge and expertise of a very experienced anesthetist) is put at the disposition of the user (clinician, anesthetist, nurse or assistant in charge) who is not obliged to follow these procedures blindly. Reversion to a manual mode is possible at any time.
• the level of experience of the person in charge or the user determines whether he or she will be allowed to configure, model or adapt any of the written procedures and/or may only be allowed to make use of existing procedures without the possibility of changing anything to the system.
• three levels of competence or experience are set : that of an expert (user of level 3) , that of a qualified user (user of level 2) and that of any user (user of level 1) .
• Changes in the procedure may be launched or triggered by the internal state of the system (i.e. the internal state of the system determines future behavior) and/or by external data such as certain patient health parameters and/or certain requests by the user.
• the modeling of procedures in the form of a script according to the invention serves to define what tools and what drugs to use, under constant observation of linked parameters and/or signals, when and how to use these without contravening constraints etc.
• the rules for constraints are such that they need to be true (not false) at every given moment.
• the system of the invention advantageously contains an Infusion Session Manager responsible for the execution and loading of tasks and procedures.
• said Manager preferably contains a User Interface (but it can optionally access any Graphic User Interface developed externally) , a Session Controller, an Infusion Controller or Drug Delivery Controller, a Datalogger Controller possibly coupled to one or more Health Monitors and a Communication Controller.
• the Infusion Session Manager can be in contact with an Archive Manager.
• the Archive Manager stores anything on the internal state of the system and stores all important data and events, so that it is possible to restart or recover actions after a power cut, a technical failure or breakdown and/or after decoupling.
• both Managers can be coupled or decoupled according to wish and are as such independently transportable units. Recovery is meant to include interruption of the actions followed by a retake exactly at the stage in the surgical procedure where one had arrived. Archiving is for instance done continuously, every second or every 5 seconds.
• the Archive Manager may be built-in in the system (i.e. one and the same program may be steering both the
• a Graphical User Interface is optional in the sense that the system can be coupled to an external Display Server (X11R5) if wanted.
• the graphical user interface may be used to trigger or start procedures (below) after input from a minimal amount of data such as patient type and health condition, type of operation, drugs to use, tools to use etc.
• the Graphical User Interface further will show the values of health parameters that are measured and/or show the possible interpretation of these values.
• the Graphical User Interface will further show any messages, comments, warnings and/or questions on a screen, such as the question to confirm a request or to confirm continuation in a given direction.
• each command given to the system via the graphical user interface has to be validated or confirmed, certainly if that command is not in the line of the expected.
• the person in charge can set via this interface the level of assistance desired, in accordance with his experience (e.g. level 1, 2 or 3) .
• the Communication Controller is there to guarantee efficient working of pumps and monitors throughout the surgical operation. This includes the fact that the system will not allow too fast switches in drug concentrations and/or drug types as the valves of the pumps will otherwise block and/or deregulate .
• the procedures [0040] comprise a set of tasks and/or commands, in this case for instance drug delivery or the measuring of health parameters, to be performed in the course of a surgical action for a given type of patient with different steps for the different phases in a given type of surgical operation.
• the strict following of a procedure and/or a possible deviation therefrom depends on the status of the patient and his or her reactions to the drugs delivered and/or the surgical operation itself and/or may depend on the choice of the anesthetist in charge .
• Drugs can be anesthetic drugs and/other drugs. Intravenous anesthetic drugs include among others hypnotics, analgesics and amnesics.
• Propofol and remifentanil are both short-acting drugs with a short half-time.
• the preferred hypnotic nowadays is propofol
• the preferred analgesic nowadays is remifentanil
• the preferred muscular relaxing drug nowadays is mivacurium but all the other anesthetic drugs or any new anesthetic drugs that may be developed can be incorporated in the system.
• the pharmacokinetic and pharmacodynamic profiles of short-acting intravenous agents allow rapid titration of drug dose to the required effect in individual patients .
• Preferred drug state models are that of Schnider (Schnider et al, 1999, Anesthesiology 90: 1502-1515) for propofol and that of Minto (Minto et al, 1997, Anesthesiology 86: 24-33) for remifentanil because both models are population pharmacokinetic sets with keo values.
• remifentanil does not cause histaminoliberation not even at the highest doses.
• the rapid decrement of remifentanil concentrations is due to a very high plasmatic clearance (10-15 min for total degradation into inactive metabolites) by non specific esterases, the presence of which is independent of age, sex, physiopathological conditions and hepatic functions (Minto et al . 1997, Anesthesiology 86: 10-23).
• Other drugs include drugs other than hypnotics, analgesics and/or amnesics that are applied in the course of a surgical operation performed under sedation or general anesthesia.
• Other drugs include but are not limited to paralyzing agents, vasodepressors, pressor substances and/or any type of drugs applied in cancer therapy, including antibiotics .
• ASA 1 or 2 The preparation of tools, drug dilutions, target concentration of anesthetic and/or other drugs to generate in accordance with for instance the type of medical intervention by surgery and/or therapy and the major steps or events therein, are effectively different for a healthy patient (ASA 1 or 2) in comparison with a patient in a bad general physical condition (ASA 3, 4 or 5) .
• ASA scores well known in the art, are most commonly used to reflect the health condition or status of a patient.
• Other input or output with respect to patient information may include data on sex, age, weight, possible allergies, ...
• Each procedure is linked to the tools needed (such as drugs, pumps, syringes and other equipment, theoretical models such as pharmacodynamic, pharmacokinetic and/or posology models) , to the conditions for use (such as material configuration, type of surgery, type of patient) , the elementary tasks to perform (such as drug delivery and registering of vital parameters), and comments, data or measurements to archive (the logbook) .
• a procedure is triggered or launched either by internal rules (interaction parameters) and/or by external events (the event table) or settings by the user (the user clicks, selects or enters data) .
• the system incorporates at least the necessary minimal safety measures or constraints (the rules for safe operation) which require that in all cases and at all times the conditions for safe use must be met.
• injection pumps can be programmed to perform certain actions automatically based on trigger combinations (parameter ranges output by a data logger) .
• the Expert (or User of level 3) is the only one allowed to launch permanent changes to the system and/or to edit the written procedures.
• an expert or User of level 3 is allowed to edit the Configuration data and/or the Knowledge Data Base containing the Infusion Sessions and any Theoretical Models to use (see Figure 1) whereas a User of Level 1 or 2 is not.
• a procedure or script of tasks and/or commands is selected and then launched by setting or specifying initial data such as patient type and health condition, type of surgical operation, drugs, tools and models to use etc. This is further referred to as configuration of the data and initialization of the request. It is possible to have the system suggest or propose part of these data such as pharmacokinetic models and for instance monitors or appropriate pumps to use .
• initial data such as patient type and health condition, type of surgical operation, drugs, tools and models to use etc.
• initial data such as patient type and health condition, type of surgical operation, drugs, tools and models to use etc.
• This is further referred to as configuration of the data and initialization of the request. It is possible to have the system suggest or propose part of these data such as pharmacokinetic models and for instance monitors or appropriate pumps to use .
• the most appropriate procedure is then selected from the knowledge data base and launched when the anesthetist or other person in charge gives a start command. This start command will start execution of the request or selected procedure .
• the Knowledge Data Base has stored theoretical models, such as pharmacodynamic, pharmacokinetic and posology models and infusion sessions.
• the latter comprise procedures but also data on tools, constraints, interactions and events further to which a modulation of the procedure is recommendable and/or necessary.
• the system is further also capable of automatically learning from data stored in the archives of various patients with similar surgical characteristics and health condition. Upon recognition of these similarities, the system then proposes the application of one or more selected procedures or algorithms, from which the parameters can be dynamically tuned by the user.
• the anesthetic procedures contain various preprogrammed commands or tasks with possibly different commands or tasks for each of the major steps, phases or events in a surgical operation.
• each type of surgery is associated with a sequence of foreseeable, reproducible and stereotype steps or events for which tasks can be preprogrammed.
• a classical intestinal surgical operation in general starts with an induction phase of general anesthesia followed by endotracheal intubation, a preparative phase of the field of operation, surgical incision followed by a high pain stimulus during the intra-abdominal phase.
• cardiac surgical operations are characterized by a sequence of such repetitive events.
• the succession of stimuli in general follows a dose scale parallel with similar individual responses.
• the stimulus associated with endotracheal intubation is generally of the same intensity as that of a skin incision.
• the maximal stimulus during an intestinal intra-abdominal surgical action is superior to the intensity of the stimulus associated with endotracheal intubation.
• other drug plasmatic concentrations and flow rates and possibly a variation in drug types or drug combinations will be suggested in the procedure.
• the same drug plasmatic concentrations and flow rates and the same drug composition may be prescribed.
• Possible predefined events of a standard surgical operation include the following: the events of sedation, induction, loss of consciousness, preintubation, haemodynamic response, the event of preparing the start of surgery, of start surgery, mean and major surgical stimulus and finally landing.
• Sedation requires a certain minimal concentration of hypnotics and/or analgesics that diminishes a patient's stress and decreases at the same time his awareness. Induction aims at finding the concentration of both hypnotics and analgesics that lead to unconsciousness. The session proposes effective concentrations of these agents according to the patient's physical condition. All the above-mentioned events are well known to a person skilled in the art.
• the, anesthetist will ask the system to save or memorize certain values such as the plasmatic drug concentration at which the patient lost consciousness, values at which a haemodynamic response was observed or at the contrary was absent etc and/or he may ask to save any internal states of the Session Manager that determine future reactions and behaviors of the system.
• This is highly useful because some of the procedural steps may for instance be in the form of "x times the concentration at which the patient lost consciousness" .
• These values may be archived in the logbook in case an Archiving Manager is used and serve as reference values for the rest of the course of the surgical operation. Patient health parameters and possible changes to the procedures in function of deviations
• one or more patient health parameters are generally followed in time.
• the advantage of following parameters in time is that useful values or numbers such as minimal and maximal values, means, coefficients of variation, a slope etc. can be obtained and/or calculated. These values are also referred to as “filtered values” .
• a "safe" range is set for each health parameter to measure (i.e. an acceptable or tolerable minimum and maximum value are defined for said parameter (s) ) .
• a Bis value should preferably fall between 45 and 60 for a given type of patient.
• ECG electrocardiogram
• ST segment myocardial ischemia detection
• invasive arterial pressure continuous registration of right pressures via a Swan-Ganz catheter in the pulmonary artery
• cardiac flux continuous registration of right pressures via a Swan-Ganz catheter in the pulmonary artery
• cardiac flux cardiac flux
• venal oxygen saturation transoesophageal echocardiography.
• Respiratory control among others includes the placement of an intubation catheter with double light, the monitoring of insufflation pressures, capnography, arterial and venal oxygen saturation in blood samples .
• a bi-spectral (Bis) analysis of an EEG may serve to survey the depth of hypnosis and unconsciousness during general anesthesia or the level of sedation (Drummond Anesthesiology 2000) .
• the Bis index can vary from 0 to 100. A Bis index close to 100 would be representative for wakefulness whereas a low Bis index is supposed to be associated with deep levels of sedation.
• a Bis index incorporates phase correlation of EEG (electroencephalogram) waves as well as EMG (electromyography) and the percentage of electric silence in the signal .
• EEG electroencephalogram
• EMG electroencephalogram
• the Bis index is often blown up, it is advantageous to measure a patient's EMG at the same time to be able to identify such blown up Bis index numbers. It is in general advisable to measure associated signals and their interactions .
• the Bis index is measured every 15 seconds and with each measurement it is verified whether the Bis index still falls within a given "safe" range, for instance 45 ⁇ Bis ⁇ 60.
• the patient's Bis index is preferably correlated with the effect-site target concentration of the hypnotic (s) .
• the patient's TOF values may be measured in function of a given flux of curare and/or the patient's MAP (mean arterial pressure).
• Changes in plasmatic concentration or at the level of the effect-site of the hypnotic (s) used can be achieved in various ways. For instance, they can be changed via a level fixed in advance (for instance plus or minus 10, 20, 30, 40, 50, 60, 70, 80 or 90 % of an actual concentration irrespective of the Bis index) or by adapting the correction to the delta-bis value (difference between the actual and the expected Bis index) In this case it suffices to increase or diminish the hypnotic proportionally. For instance, a delta-bis of +5 will provoke an increase of 5 % of the plasmatic concentration, and a delta-bis of -20 will provoke a decrease by 20%.
• a level fixed in advance for instance plus or minus 10, 20, 30, 40, 50, 60, 70, 80 or 90 % of an actual concentration irrespective of the Bis index
• the delta-bis value difference between the actual and the expected Bis index
• the system also registers for instance, at the command of the person in charge, minimal and/or maximal limit values of physiological parameters recorded by the patient health monitor when reaching and/or exceeding a limit concentration of anesthetics and/or other drugs (see above) .
• Constraints and safety measures The system according to the invention includes a minimal set of constraints or safety measures . These help to avoid undesired automatic actions. This concept is also referred to as the safety and/or control concept .
• An example of a safety measure is that the system will not allow the drop of an analgesic below a minimal concentration during the course of the operation. For instance, the brutal recovery of a patient is always possible when the propofol target is below 1.5.
• constraints foreseen in the system of the invention: time constraints, calculation constraints and constraints of appropriate functioning.
• the first include the calculation time, the reaction time (i.e. the time needed for a device to react to the command given, to change its current state and/or to stop its current actions) and the period of acquisition (i.e. the minimal period for a monitor to register something) .
• Calculation constraints guarantee that every second the necessary measurements are effected, and guarantees that calculated flow rates correspond to actual flow rates of a pump before any (further) changes to said flow rate are permitted.
• delays are imposed by the time necessary to command for instance a pump and by the time needed to calculate the actual infusion of a drug realized following a modification to the system.
• no change to the system is allowed before the calculated flow rate or the flow rate set corresponds to the actual flow rate of a pump.
• at least 10 seconds are preferably allowed at the level of pump control as the valves would otherwise deregulate and/or block. This delay is fixed and can not be modified by the person in charge .
• the delay needed for adequate pump control may vary from about 10 to about 30 seconds.
• Another safety measure that can be included is the comparison of actually measured values with for instance median values, mean values (for instance the mean value over the preceding minute) , moving averages or moving medians registered by the patient health monitor over a given period of time or any other calculated parameter of interest . These values are also referred to as “filtered” values.
• a "normal” value and/or a "safe” range is defined for each of the parameters. Drug concentrations may then be automatically adapted whenever they depart from said normal value and/or are no longer contained within the given "safe” range.
• the actual concentration of anesthetics and/or other drugs may be automatically changed whenever the Bis index is lower than 45 or higher than 60 and/or whenever the MAP departs from its normal value (see Table 2) .
• the MAP departs from its normal value (see Table 2) .
• Another safety measure may exist in the automatic and rapid decrease of the propofol target concentration or flow rate according to the BIS values as such that the propofol concentration will not drop below a predetermined value of for example 1.5 ⁇ g/ml .
• Still another safety measure may exist in the warning of the person in charge by way of a signal such as a sound or by way of a written message in case of an inappropriate handling or instruction or in case certain health parameters deviate unexpectedly. Any automatic adaptation of a parameter could be advertised by an alarm signal .
• a reliable measurement of health parameters such as the Bis index
• the quality of said signal and/or the value of other related signals can be taken into consideration. For instance, if the Bis value is not corresponding to a given EMG value, this Bis value is considered unreliable.
• the system will provoke the following actions: (i) warn the user and (ii) leave the automated closed-loop and revert to manual mode. This is done following the observation that a constraint is false (and not true) .
• a check will be performed on a regular basis, for instance each second, each 5 seconds, each 10 to 30 seconds, each minute or every 5 minutes .
• the reliability of a signal or parameter may be determined or defined by the quality of its signal, by its relation with other related signals or parameters and/or by the deviation from a normal value and/or from a safe range .
• Still another safety measure may exist in the warning in case a drug concentration is set (by the person in charge) outside the normal range used for that drug.
• the system of the invention has hitherto been mainly explained for applications in intravenous anesthesia.
• the system is, however, equally well applicable to other medical fields such as for instance cancer therapy wherein drugs and possible also antibiotics may be intravenously administered.
• Example 1 a healthy patient subjected to a standard type of surgery
• ASA2 patient in good health
• Event sedation 0.5 ⁇ g/ml propofol
• Event induction 1.5 ⁇ g/ml propofol + 2ng/ml remifentanil.
• Event loss of consciousness maintaining the propofol concentration at the level whereby loss of consciousness was registered. The concentration whereby loss of consciousness is obtained will be memorized on the demand of the person in charge .
• Event preintubation increasing the concentration of remifentanil up to a level suited with respect to the patient's age, physical condition, the adjuvants being administered and registered by the procedure, e.g. increase up to 4ng/ml for a patient that is sensitive.
• Example 2 an unhealthy patient subjected to cardiac surgery
• Event preintubation increasing the concentration of remifentanil up to 3 ng/ml .
• the actually needed value is again memorized and will have consequences for the rest of the procedure, for instance in case of a haemodynamic response or in case one needs more than 3 ng/ml of remifentanil
• Event haemodynamic response + 1 ng/ml remifentanil
• Event preparing start surgery returning to the level of hypnotic that induced loss of consciousness, with or without a level of analgesic .
• Event start surgery returning to the concentration of hypnotic (s) and analgesic (s) registered for an intubation when no haemodynamic response was invoked by intubation or going back to the intubation level + the increase in case of a haemodynamic response
• Mean surgical stimulus remifentanil incision level * 1.25
• Major surgical stimulus remifentanil incision level during a mean surgical stimulus * 1.5
• Landing synchronized return to the level of hypnotic that invoked unconsciousness at the effect-site together with an analgesic level associated with a lack of major respiratory depression

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• 2003
  • 2003-12-24 EP EP03447308A patent/EP1547631A1/de not_active Withdrawn
• 2004
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  • 2004-12-21 ES ES04802156T patent/ES2293366T3/es active Active
  • 2004-12-21 WO PCT/BE2004/000180 patent/WO2005061028A1/en active IP Right Grant
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